Stable isotope analysis and U-Th dating of late glacial and Holocene lacustrine sediments from central Turkey

Dean, Jonathan R. (2014) Stable isotope analysis and U-Th dating of late glacial and Holocene lacustrine sediments from central Turkey. PhD thesis, University of Nottingham.

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Water is a politically sensitive resource in the Near East and water stress is increasing. It is therefore vital that there is a strong understanding of past hydrological variability, so that the drivers of change can be better understood, and so that the links between the palaeoclimate and archaeological records in this key region in the development of human civilisation can be investigated. To be of most use, this requires high resolution records and a good understanding of palaeoseasonality.

A sediment sequence spanning ~14,000 years has been retrieved from Nar Gölü, a lake in central Turkey. This thesis presents isotope data from carbonates, diatoms and bulk organic matter, in particular focussing on oxygen isotope (δ18O) analysis of carbonates (which detailed monitoring of the modern lake system shows to be a strong proxy for water balance) and comparing δ18Ocarbonate and δ18Odiatom data in order to examine palaeoseasonality. Improved techniques for the interpretation of carbonate isotope records of mixed mineralogies and the mass balance correction of diatom samples contaminated with minerogenic material are also proposed.

Due to the high resolution δ18Ocarbonate data, it was possible to show that the rapidity of the Younger Dryas to Holocene transition at Nar Gölü was similar to that seen in North Atlantic records and that centennial scale arid events in the Holocene seem to occur at the time of cold periods in the North Atlantic. Taken together, this suggests a strong teleconnection between the two regions. However, the longer duration of the aridity peaks ~9,300 and ~8,200 years BP at Nar Gölü, compared with the more discrete cooling events at this time in the North Atlantic, suggest that there are additional controls on Near East hydroclimate. There is a multi-millennial scale trend of increasing δ18Ocarbonate values from the early to late Holocene. This ‘Mid Holocene Transition’ has previously been identified in the Near East, however here it is demonstrated that water balance and not a shift in the seasonality of precipitation was the primary cause. Finally, for the first time, the stability of Near East climate in the early Holocene is robustly demonstrated, suggesting that this could have been a key enabler of the development of agriculture at this time.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Jones, M.
Metcalfe, S.E.
Subjects: G Geography. Anthropology. Recreation > GB Physical geography
Faculties/Schools: UK Campuses > Faculty of Social Sciences, Law and Education > School of Geography
Item ID: 14090
Depositing User: EP, Services
Date Deposited: 04 Nov 2014 13:12
Last Modified: 16 Sep 2016 18:51

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